Suppressing Crystallinity by Nanoconfining Polymers Using Initiated Chemical Vapor Deposition

Abstract

Poly­(1H,1H,2H,2H-perfluorodecyl acrylate) (PPFDA) is incorporated within a sintered mesoporous network of TiO2 nanoparticles via initiated chemical vapor deposition (iCVD). iCVD PPFDA grows uniformly on the pore surface of the mesoporous TiO2 (25 nm pore diameter, 2–4 μm thick), resulting in up to 91% of the pore volume being filled. This leads to a high TiO2 loading (58 vol %, 67 wt %) in the PPFDA–TiO2 nanocomposite and a large decrease in the PPFDA crystallinity by >93% compared to the bulk polymer film. The significantly suppressed crystallinity is attributed to the nanoconfinement of polymer chains in the tortuous, interconnected nanopore channels that frustrates chain alignment, and from the large interfacial energy difference between PPFDA fluoropolymer and hydroxylated TiO2 that impedes heterogeneous nucleation for crystal growth.

Nanoscale control by chemically vapour-deposited polymers

“…129,130 By optimizing processing conditions, iCVD can infill porous and textured substrates. The infiltration of iCVD fluoropolymers into TiO2 nanoparticles matrices produces composite films with high loadings of inorganic particles 131 and bulk hybrid composites acting as superhydrophobic sponges 132 . Modified iCVD processes can achieve global and local planarization of surfaces features on silicon wafers.…”

Data‐driven prediction and optimization of liquid wettability of an initiated chemical vapor deposition‐produced fluoropolymer

“…In all deposition runs, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) reveal the chemical composition and stoichiometry expected of PPFDA, results of which have been shown previously. 15 In terms surface morphology, scanning electron microscopy (SEM) show the formation of micro-and nano-scale worms.…”

“…In general, the surface polymerization process allows iCVD to deposit thin uniform coatings that conform to the substrate topology 7,8 . Besides planar substrates like silicon wafers, micro‐ and nano‐scale porous materials can also be conformally coated by iCVD 7,13–16 . By controlling the relative rates of reactant diffusion and polymerization, uniform growth can be achieved.…”

Kinetics of All-Dry Free Radical Polymerization under Nanoconfinement

“…Furthermore, conformal coatings have been applied in a substrate-independent manner onto silicon microtrenches (with aspect ratio <10), − block copolymer membranes (with aspect ratio <80), self-assembled anodized aluminum oxide (AAO) membranes (with aspect ratios of ∼250), , and track-etched membranes [with aspect ratios approximately O (10 1 ) to O (10 2 )]. , Keeping the system in a reaction-limited regime (as opposed to a mass-transfer-limited regime) was found crucial in forming conformal coatings inside nanoporous geometries, eventually achieving complete filling of pores . That tight integration of polymers and inorganic materials has important implications for properties of the composite materials, including polymer glass transition temperature, polymer crystallinity, and specific capacitance …”

“…4,17 Keeping the system in a reaction-limited regime (as opposed to a mass-transfer-limited regime) was found crucial in forming conformal coatings inside nanoporous geometries, eventually achieving complete filling of pores. 18 That tight integration of polymers and inorganic materials has important implications for properties of the composite materials, including polymer glass transition temperature, 19 polymer crystallinity, 20 and specific capacitance. 8 Both conformal coating and complete filling of pores rely on the arrival of vapor phase reactants to the surface by non-lineof-sight diffusion, i.e., Knudsen diffusion, under modest vacuum conditions and the limited probability of reaction upon a single surface collision.…”